[Bug tree-optimization/51990] ICE in copy_reference_ops_from_ref

[vries at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51990

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |UNCONFIRMED
     Ever Confirmed|1                           |0

--- Comment #5 from vries at gcc dot gnu.org 2012-01-25 11:41:50 UTC ---
(In reply to comment #4)
> (In reply to comment #1)
> I think there are a lot of bugs lurking in the compiler with respect to
> not handling WITH_SIZE_EXPR (which incidentially isn't a handled-component,
> nor tcc_reference ...).  You btw. also need to handle re-materializing
> them in create_component_ref_by_pieces_1.

Indeed. Using the proposed patch and this example:
...
int y;
extern int foo (int, ...) __attribute__((pure));

int
zzz (char *s1, char *s2, int len, int *q, int c)
{
  int z = 5;
  unsigned int i,  b;
  struct s { char a[z]; };
  struct s x; 
  int y_tmp = 5;

  for (i = 0; i < len; i++)
    s1[i] = s2[i];

  b = z & 0x3;

  len += (b == 0 ? 0 : 1) + z;

  *q = len;

 if (c)
   y_tmp = foo (z, x, x) + 4;

 z = foo (z, x, x) + 4;
 y = y_tmp;

 return  z;
}
...

I hit this ICE:
...
test2.c: In function ‘zzz’:
test2.c:5:1: internal compiler error: in create_component_ref_by_pieces_1, at
tree-ssa-pre.c:2925
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
...

tentative patch:
...
Index: tree-ssa-pre.c
===================================================================
--- tree-ssa-pre.c (revision 183325)
+++ tree-ssa-pre.c (working copy)
@@ -2780,6 +2780,7 @@ create_component_ref_by_pieces_1 (basic_
     case REALPART_EXPR:
     case IMAGPART_EXPR:
     case VIEW_CONVERT_EXPR:
+    case WITH_SIZE_EXPR:
       {
     tree folded;
     tree genop0 = create_component_ref_by_pieces_1 (block, ref,
@@ -2787,8 +2788,12 @@ create_component_ref_by_pieces_1 (basic_
                             stmts, domstmt);
     if (!genop0)
       return NULL_TREE;
-    folded = fold_build1 (currop->opcode, currop->type,
-                  genop0);
+
+    folded
+      = (currop->opcode == WITH_SIZE_EXPR
+         ? fold_build2 (currop->opcode, currop->type, genop0, currop->op0)
+         : fold_build1 (currop->opcode, currop->type, genop0));
+
     return folded;
       }
       break;
...